The present invention relates to a disc brake, in particular a disc brake for utility vehicles, having a brake caliper which straddles a brake disc at least in sections at its periphery, a brake application device, which is completely or partially arranged in the brake caliper, for applying the brake, and a wear adjusting system, which is arranged in the brake caliper, for adjusting the air play between brake pads and the brake disc. The adjusting system includes at least one adjusting device, preferably in the form of a rotary device.
A disc brake of the above-mentioned type is known from WO 02/14708, which disc brake can be embodied as a sliding caliper, a pivoting caliper, or a fixed caliper brake, in particular also with a displaceable brake disc.
To compensate for brake lining and/or brake disc wear, a wear adjusting system is arranged in the brake caliper, by which adjusting system the brake pads can be adjusted in the direction of the brake disc such that the spacing between the friction face of the brake lining of the brake pad and the brake disc, the so-called air play, is preferably kept constant.
In WO 02/14708, the adjusting system has at least one adjusting device in the form of a rotary device, which in one embodiment is driven electromotively and in another embodiment is driven mechanically. In the latter case, the brake application device is actuated by way of a brake lever coupled thereto.
Both functioning principles, i.e., electromotive and mechanical, have in common that the adjustment process is limited as a function of load, that is to say the adjustment is interrupted when the brake linings bear with frictional engagement against the brake disc.
The electromotive adjustment is, naturally, associated with a certain degree of design-related and production-related expenditures. This also encompasses special measures which are necessary to satisfy the harsh operating conditions under which disc brakes for utility vehicles are conventionally used.
The direct functional dependence of the wear adjusting system on the actuation of the brake application device does not allow an excess travel to be overcome. Moreover, the excess travel is under some circumstances only reduced once the adjusting system has been actuated several times, so that the functionality of the adjusting system is not optimally provided from the start.
In addition, the air play is conventionally adversely affected by the summing of several individual, for example production-related, tolerances. This also impedes optimum use of the wear adjusting system.
The present invention is, therefore, based on the object of further developing a disc brake of the above-mentioned type such that the function of the wear adjusting system is optimized with little structural expenditure.
This, and other, objects are achieved by a disc brake having a brake caliper which straddles a brake disc at least in sections at its periphery, a brake application device, which is completely or partially arranged in the brake caliper, for applying the brake, and a wear adjusting system, which is arranged in the brake caliper, for adjusting the air play between brake pads and the brake disc. The adjusting system includes at least one adjusting device, preferably in the form of a rotary device. A rechargeable force store is provided as a drive for the wear adjusting device.
The new disc brake is, firstly, characterized in that the improvement in functionality of the wear adjusting system may be provided using very simple structural means. In addition to cost-effective production and assembly, a further advantage to be highlighted is an improved robustness and relatively low susceptibility to failure, which naturally has a notable effect on a longer service life.
In principle, the wear adjusting system, that is to say of the rotary device, is actuated only indirectly as a function of the actuation of the brake application device, that is to say, the rotary device only becomes active when the air play has exceeded a certain nominal value.
The mechanical, load-dependent functioning of the new adjusting system makes it possible for any excess travel that may be present to be fully overcome already during a first actuation, thus resulting in an improvement in operational safety.
Also, the aggregate tolerance, discussed with regard to the prior art, which results from the direct actuation of the wear adjusting system by way of the brake application device and likewise impedes optimum functioning of the adjusting system, is no longer present as a result of the invention.
According to one advantageous refinement of the invention, it is provided that the force store is composed of a spring, in particular a spiral spring. The spiral spring is preferably fastened at its center to a positionally fixed pin, which is preferably connected to the brake caliper, and at the outside to a sleeve, which is arranged concentrically with respect to the pin. The sleeve is provided with an outer toothing and corresponds to the rotary drive, wherein, in the functional case of the internally-situated spiral spring, the sleeve rotates about the pin under the spring force of the spiral spring.
The force store is connected to a blocking device, which is unlocked when the air play exceeds a nominal value. In this case, the rotary device is actuated by the force store, preferably the spiral spring, such that the attached brake linings are moved indirectly towards the brake disc. The unlocking of the blocking device as the brake application device is actuated is preferably effected by way of a lever or another component, which is preferably attached to the blocking device. Here, the blocking device may be mounted by use of a disc so as to be axially displaceable and yet rotationally fixed on a shaft. The blocking device may have a crown toothing, which engages in a blocking toothing which is matched to the crown toothing, is positionally fixed in relation thereto, and is provided, for example, in the brake caliper.
The simple structural design is also notable here in particular because the function of the wear adjusting system is triggered by the actuation of the application device, and so no additional function parts are necessary for this purpose.
The shaft which supports the blocking device may be embodied as a coupling shaft, by which, in the case of the disc brake being embodied as a fixed caliper brake with a displaceable brake disc, adjusting devices arranged on both sides of the brake disc are actuated simultaneously, specifically by way of a common force store.
The force store, preferably in the form of a spiral spring, is designed such that, as the brake linings wear, its energy reserve, that is to say the spring force, is used up to such an extent that a final adjustment is still possible. By re-tensioning the spiral spring, that is to say turning it back counter to the rotational direction in the functional case, the force store is recharged.
Further advantageous embodiments of the invention are described and claimed herein.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.